Got a BF XR6 ute with a 4spd auto... had it in for it's 1st service today, with a few minor cosmetic probs, and one other drama..

In the mornings, or when not driven for an hour or so, I have a prob where the auto seems like it hits neutral when changing between gears...
If i drive slowly, it's like an "over-rev" (for want of a better term)
If I give it a bit of stick, it thumps into the next gear , a bit like a BA auto.
The service guys say they uploaded a new shift pattern to the car , yet it did the same thing as I drove out their driveway...
The BF 4sp tranny was supposed to be a vast improvement over the BA jobbie, since the XR6T and XR8's got the 6 speed...

I went for the 6 speed, and it was the best decision i made. The 4 speed was always fine but after a late minute change of heart to take a 6 speed for a drive, i was sold. Im able to keep up with the standard Turbo's and beat them off the line.

I went for the 6 speed, and it was the best decision i made. The 4 speed was always fine but after a late minute change of heart to take a 6 speed for a drive, i was sold. Im able to keep up with the standard Turbo's and beat them off the line.

Hmmm I thought the 6 speed was only available with the turbo and XR8.. and you've got one in a XR6NA??

Is what your auto is doing is whats called flaring, well the transmission is slipping so the engines rpm increases or flares.

The transmission hydraulic system is used for control purposes to accurately predict the achievement of on-coming clutch torque capacity based on a comparison of the modeled volume of supplied fluid to a reference volume representing the actual volume of the on-coming clutch, and in which the reference volume for each type of shift is adaptively adjusted based on input speed aberrations observed during shifting.

If input speed flaring occurs due to an underestimated reference volume, the reference volume is adaptively increased based on the volume of fluid supplied to the on-coming clutch between the initial detection of flaring and a detection of maximum flaring. If the input speed does not flare, but an early pull-down or overlap is detected, the reference volume is adaptively decreased based on the volume of fluid supplied to the on-coming clutch between the initial detection of pull-down or overlap and the expected achievement of on-coming clutch torque capacity.

So basically the transmission underestimates the fluid volume required to change gear, this volume comes from the pressure built up in the transmission from its pump (each gear change has a different amount of pressure to change into the next gear).

If the required pressure is not met, then it flares, so pressure is increased and then there is a violent or sudden gear change. Now with the newer trasmissions they are electronically controlled so its possible its a bad TR/MLP sensor.

My automatic transmission did it on rare occasions but then I did a full transmission service on it (new filter, 12ltr of fluid and flush), now it hasnt done it since.

Changing shift points will not fix this as its an electronic or sensor problem. Sometimes a vehicle fault code can be found and the problem can be fixed, other times its a ghost within the system.

Is what your auto is doing is whats called flaring, well the transmission is slipping so the engines rpm increases or flares.

<snip valuable info>

Changing shift points will not fix this as its an electronic or sensor problem. Sometimes a vehicle fault code can be found and the problem can be fixed, other times its a ghost within the system.

Many thanks for that info.. I'l print it out, and show the service dude.
For what it's worth, whatever he did to it did improve it, but it's still "flaring" between 2nd and 3rd early on, probably only once per driving session. It seems to be ok after it's slipped once...

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